1. Field of the Invention
The present invention relates to an engine working machine assembly in which a working machine such as a generator, a compressor and the like is adapted to be driven by an internal combustion engine and more specifically to an air-cooled type cooling system for an engine working machine assembly which employs an air-cooled engine as an internal combustion engine.
2. Prior Art
A conventional engine working machine assembly is disclosed in U.S. Pat. No. 2,543,541 (Patented Feb. 27, 1951). In this engine working machine assembly, a machine area and a fan area are partitioned within a casing thereof. A radial internal combustion engine (simply referred to as an engine hereinafter) and a generator are disposed within the machine area, and an axial fan is disposed within the fan area. a ventilation inlet opened to the fan area is in communication with an exterior space outside the casing through the fan area and the machine area so that cooling air can be delivered by the axial fan to the engine as well as the generator in the machine area and cool them therein.
As a means for reducing noise of the engine working machine assembly having the construction mentioned above, the following is known by the inventors of the present invention.
An exhaust muffler and a muffler cover are arranged in the machine area so that the exhaust muffler is accommodated within the muffler cover to provide a muffler cooling air passage therebetween, and the muffler cooling air passage and the exterior space outside the casing are connected in series with the interior space within the machine area. First the cooling air is delivered by the axial fan to the machine area to cool the engine and the generator therein and then to the muffler cooling air passage to cool an exhaust gas. Accordingly, a volumetric flow of the exhaust gas is decreased so as to reduce the noise of the exhaust gas.
However, in this case, since the flow resistance of the cooling air gets large by the amount thereof flowing through the muffler cooling air passage, the quantity of the cooling air gets decreased thereby correspondingly and cooling efficiency for the engine and the generator gets lowered disadvantageously.